Such a luminaire and such an assembly are known per se. They are used inter alia in ceiling lighting for illuminating objects such as, for example, in a shop window, in a shop, in an exhibition space, for example for illuminating artistic objects, or in a showroom, for example for illuminating comparatively large objects, for example motor vehicles. Such an assembly or luminaire is also used for wall illumination so as to illuminate objects sideways, or for floor illumination, for example on stages, for illuminating objects or persons. Furthermore, the assembly and luminaire are used as backlights for, for example, (picture) display devices such as, for example, (PA)LC displays or video walls, and as office lighting or as a luminaire for enhancing the visual appearance of an object. Usually, an assembly as mentioned above comprises a plurality of luminaires mounted next to one another, often in the form of a number of coupled squares.
A luminaire of the type mentioned above has a major drawback. The luminaire has a surface with a non-homogeneous light distribution. As a result of this, the object is not evenly illuminated, which is undesirable.